substance: boron compounds with lanthanides
property: properties of lanthanide hexaborides: CeB6
Structure, chemical bond
There are three phases in the temperature versus magnetic field diagram [83T2]); (i) high temperature phase
characterized by a pronounced Kondo effect [80K, 80T], (ii) an intermediate phase, in which two kinds of
hyperfine fields are assumed to be due to an ordering of the higher order multipole moments (antiquadrupolar
ordering) of Ce ions, while the the magnetic dipole moment has only the uniform component [83T2], (iii) lowtemperature phase with a long-range magnetic order [82B].
Magnetic field – temperature phase diagram at ambient pressure in Fig. 1 [85B]. For phase diagrams at higher
pressures see reference.
NMR study of CeB6, temperature dependence of the nuclear relaxation time and correlation time of Ce moments
in [83T2].
NMR study of the spin structure in CeB6 [83T1].
Electronic properties
Calculation of the electronic band structure (FLAPW method) and positron annihilation in CeB6 (compared with
LaB6) [89K].
Electronic band structure in Fig. 2 [89K].
energy gap
Eg
45 meV
T =13...53 K
electron-tunneling
98A
Electron-tunneling studies compared with SmB6, EuB6, SrB6 in [98A].
CeB6 possesses a magnetic moment like SmB6 and EuB6 but in contrast to SrB6 [98A].
Richardson plot for CeB6 (and LaB6) with excess B (CeB6.07 and LaB6.06) compared with pure crystals in Fig. 3
[96O1].
Lattice properties
anisotropic thermal parameters for the B atom
(in Å2)
U11
U22
0.00308
0.00312
0.0045
0.0049
T = 100 K
T = 300 K
T = 100 K
T = 300 K
from diagram in [93T]
85S1
calculated (one specific model)
experimental
calculated
experimental
calculated
experimental
85T
elastic constants
(in 1011 dyn cm−2)
c11
c12
c44
40.30
40.6
−8.59
−9.3
9.91
7.8
83G
85S2
Optical properties
Differences between LaB6 and CeB6 by means of spectroscopic ellipsometry [86V].
Further properties
Entropy in [86B].
Search for rugged, efficient photocathode materials (CeB6 and LaB6) [92B].
melting point
Tm
2550 °C
96G
Debye temperature
ΘD
381 K
T = 300 K
85S2
For Einstein temperatures of metal hexaborides, see Fig. 4.
microhardness
HK
2250 kg mm−2
2150 kg mm−2
T = 300 K
cube, average value; load 50 g
cube, average value; load 100 g
96G
High temperature hardness of single crystals of LaB6, CeB6, PrB6, NdB6 and SmB6 [99O].
Evaporation rates of pure CeB6 and CeB6 with excess B compared with corresponding LaB6 crystals in Fig. 5
[96O1].
Thermionic emission properties of CeB6 (compared with LaB6) in [96O1, 96O2].
Susceptibility vs. magnetic field at different T in Fig. 6 [85B].
Magnetization vs. temperature in Fig. 7 [80K].
Susceptibility vs. temperature in Fig. 8 [80K].
Pressure dependence of Néel and antiferroquadrupolar temperatures in Fig. 9 [85B].
References:
80K
80T
82B
83G
83T1
83T2
85B
85S1
85S2
85T
86B
86V
89K
92B
93T
94K
96G
96O1
96O2
98A
99O
99T
Kawakami, M., Kunii, S., Komatsubara, T., Kasuya, T.: Solid State Commun. 36 (1980) 435.
Takase, S., Kojima, K., Komatsubara, T., Kasuya, T.: Solid State Commun. 36 (1980) 461.
Burlet, P., Rossat-Mignod, J., Effantin, J.M., Kasuya, T.: J. Appl. Phys. 53 (1982) 2194.
Goto, T., Tamaki, A., Kunii, S., Nakajima, T., Fujimura, T., Kasuya, T., Komatsubara, T., Woods,
S.B.: J. Magn. Magn. Mater. 31 (1983) 419.
Takigawa, M., Yasuoka, H., Tanaka, T., Ishizawa, Y.: J. Phys. Soc. Jpn. 3 (1983) 728.
Takigawa, M., Yasuoka, H., Tanaka, T., Ishizawa, Y., Kasaya, M., Kasuya, T.: J. Magn. Magn.
Mater. 31-34 (1983) 391.
Brandt, N.B., Moshchalkov, V.V., Pashkevich, S.N., Vybornov, M.G., Semenov, M.V., Kolobyanina,
T.N., Konovalova, E.S., Paderno, Yu.B.: Solid State Commun. 56 (1985) 937.
Sato, S.: J. Magn. Magn. Mater. 52 (1985) 310 (structural data of CeB6).
Smith, H.G., Dolling, G., Kunii, S., Kasaya, M., Liu, B., Takegahara, K., Kasuya, T., Goto, T.: Solid
State Commun. 53 (1985) 15.
Takegahara, K., Kasuya, : Solid State Commun. 53 (1985) 21.
Borovikova, M.S., Fesenko, V.V.: J. Less-Common Met. 117 (1986) 287. ( Proc. 8th Int. Symp.
Boron, Borides, Carbides, Nitrides and Rel. Compounds, Tbilisi, Oct. 8 - 12, 1984)
van der Heide, P.A.M., ten Cate, H.W., ten Dam, L.M., der Groot, R.A., de Vroomen, A.R.: J. Phys.
F: Met. Phys. 16 (1986) 1617.
Kubo, Y., Asano, S.: Phys. Rev . B 39 (1989) 8822.
Bamford, D.J., Bakshi, M.H., Deacon, D.A.G.: Nucl. Instrum. Methods A 318 (1992) 377.
Trounov, V.A., Malyshec, A.L., Chernyshov, D.Yu., Korsukonva, M.M., Gurin, V.N., Aslanov, L.A.,
Chernychev, V.V.: J. Phys.: Condens. Matter 5 (1993) 2479.
Korsukova, M.M.: Proc. 11th Int. Symp. Boron, Borides and Rel. Compounds, Tsukuba, Japan,
August 22 - 26, 1993, Jpn. J. Appl. Phys. Series 10 (1994), p. 15.
Gurin, V.N., Derkachenko, L.I., Korsukova, M.M., Nikanorov, S.P., Jung, W., Müller, R.: Sov. Phys.
Solid State 38 (1996) 1508.
Otani, S., Ishizawa, Y.: J. Alloys Compounds 245 (1996) L18.
Otani, S., Souda, R., Ishizawa, Y.: J. Ceram Soc. Jpn. Inter. Ed. 104 (1996) 1088.
Ambler, B., Fisk, Z., Sarrao, J.L., v. Molnar, S., Meisel, M.W., Sharifi, F.: Phys. Rev. B 57 (1998)
8747.
Otani, S., Nakagawa, H., Nishi, Y., Kieda, N.: J. Solid State Chem. (2000) (Proc. 13th Int. Symp.
Boron, Borides and Rel. Compounds, Dinard, France, Sept. 1999).
Takahashi, Y., Ohshima, K., Okamura, F.P., Otani, S., Tanaka, T.: J. Phys. Soc. Jpn. 68 (1999) 2304.
Fig. 1.
CeB6. Magnetic field vs. T phase diagram at ambient pressure [85B]. AFM: antiferromagnetic, PM:
paramagnetic, AFQ: antiferroquadrupolar.
25
CeB6
, ,
,
Magnetic field H [kOe]
20
,
H||[100]
H||[110]
H||[100]
H||[110]
15
10
5
III-AFM
0
1.0
1.5
TN
2.0
II-AFQ
TQ
2.5
3.0
3.5
Temperature T [K]
I-PM
4.0
4.5
Fig. 2.
CeB6. Calculated electronic band structure FLAPW (full-potential linearized augmented-plane-wave) method
[89K]. Dashed line: Fermi level.
1.2
CeB6
1.0
EF
0.8
Energy E [Ry]
0.6
0.4
0.2
0
– 0.2
– 0.4
M
Σ
Γ ∆
Χ Z
M
T R
S
Wavevector k
Χ ∆
Γ
Λ
R
Fig. 3.
LaB6, CeB6. Richardson plots for LaB6 and CeB6 crystals with excess B compared with pure material [96O1].
Crystal diameter: 0.5 cm.
2⋅10
–6
–6
crystal
8
anode
10
–2 –2
ic / T [A cm K ]
6
A
2
4
2
10
LaB6
LaB6.06
CeB6
CeB6.07
–7
8
6
4⋅10
–8
0.58
0.60
0.62 0.64 0.66 0.68 0.70
–1
–3 –1
Inv. temperature T [10 K ]
0.72
Fig. 4.
Metal hexaborides. Characteristic Einstein temperatures of the Ln atoms vs. atomic number of the Ln element;
full circles [94K]; triangles [99T].
150
LnB6
Ln = La
Einstein temperature
E [K]
140
130
120
Ce
Pr
Nd
Eu
Sm
110
100
90
56
59
Gd
62
65
Ln atomic number
Yb
68
71
Fig. 5.
LaB6, CeB6 :B. Evaporation rate of pure LaB6 and CeB6 with excess B compared with the corresponding pure
crystals [96O1].
10
1
water-cooled anode
–1
Evaporation rate [µ m(100 h) ]
crystal
–1
10
–2
10
10
LaB6
LaB6.06
CeB6
CeB6.07
–3
4⋅10
–4
1300
1350
1450
1400
Temperature T [°C]
1500
1550
Fig. 6.
CeB6.Magnetic susceptibility χ vs. magnetic field H in arbitrary units. Typical curves for specific temperature
ranges. For the symbols at the peaks see Fig. 1 [85B].
CeB6
H||[110]
T < TN
Susceptibility χ
H||[100]
T < TN
H||[100]
H||[110]
TN < T < TQ
H||[100]
H||[110]
T > TQ
Magnetic field H
Fig. 7.
CeB6. Specific magnetization in 750 Oe vs. T; solid circles, [100]; open circles, [110]; triangles, [111].[80K].
1.4
3 –1
Spec. magnetization σ [G cm g ]
1.2
CeB6
H = 750 Oe
[100]
[110]
[111]
1.0
0.8
0.6
0.4
0.2
0
1.0
1.5
2.0
2.5
3.5
3.0
Temperature T [K]
4.0
4.5
Fig. 8.
CeB6. Inverse magnetic susceptibility 1/χg (in CGS-emu) vs. T. Circles, experimental results; dotted line,
calculated. [80K].
3.0
0.4
CeB6
–3
Inv. susceptibility χ–1
g [10 g cm ]
2.0
0.3
5
5
–3
Inv. susceptibility χ–1
g [10 g cm ]
2.5
1.5
1.0
0.2
0.1
0.5
0
200
400
600
Temperature T [K]
800
1000
0
20
40
Temperature T [K]
60
80
Fig. 9.
CeB6. Néel temperature and antiferro-quadrupolar temperature vs. pressure [85B].
3.4
CeB6
TQ
Transition temperature TN , TQ [K]
3.2
3.0
2.4
2.2
TN
2.0
1.8
0
2
4
6
8
8
Pressure p [10 Pa]
10
12